For years, people have attempted to solve the problems associated with the destruction, processing, and handling (hereafter collectively referred to as xe2x80x9cprocessingxe2x80x9d) of hazardous and toxic waste (hereafter collectively referred to as xe2x80x9chazardous wastexe2x80x9d). To date, the primary means of processing hazardous waste is to burn such waste in an incinerator. Incinerators, however, have their drawbacks. First, incinerators are not capable of processing certain types of hazardous waste such as polychlorinated biphenyls, hydrogen fluoride, bromines, complex organics, and pesticides. Second, incinerating some hazardous waste results in the generation of yet other hazardous byproducts or pollutants which take the form of a liquid, solid, or gas, such as heavy metals, dioxins and furans which are known to cause cancer in humans. Third, it has been difficult for municipalities and counties to identify acceptable locations within their communities to locate an incinerator, because few, if any, communities find it desirable to locate an incinerator in their own xe2x80x9cbackyard.xe2x80x9d Fourth, it is sometimes assumed that hazardous waste can be brought to an incinerator for processing. However, some hazardous waste is so dangerous it cannot be moved even a short distance to an incinerator. In yet other instances, hazardous waste can be moved but, given a choice, it should not be moved. Moving waste, even a short distance, raises the possibility that a spill may occur. Further, burning waste in an incinerator has other drawbacks. Most hazardous waste sites which use incinerators also require special landfills where hazardous byproducts (e.g., fly and bottom ash) from the incinerator must be buried and continually maintained in accordance with federal, state and local government regulations. Operating such a landfill is complicated, risky and costly.
Existing systems have attempted to provide alternatives to incineration. One such system is disclosed in U.S. Pat. No. 5,534,659 to Springer, et al., (xe2x80x9cSpringerxe2x80x9d) for example. Co-pending and commonly assigned U.S. patent application No. 09/667,673 entitled xe2x80x9cMethod And System For Safely Processing Hazardous Wastexe2x80x9d (hereafter referred to as xe2x80x9cco-pending applicationxe2x80x9d) addresses some of the shortcomings and inadequacies of existing systems. Co-pending U.S. Patent Application No. entitled xe2x80x9cMethods And Systems For Safely Processing Hazardous Wastexe2x80x9d (hereafter referred to as xe2x80x9cco-pending applicationxe2x80x9d) addresses some of the shortcomings and inadequacies of existing systems.
Springer deals with a fixed waste processing system. By xe2x80x9cfixedxe2x80x9d system is meant a system which is not designed or constructed to be frequently moved from one location or position to another. Said another way, fixed systems are not designed or constructed to be rugged or mobile. Rather, existing fixed systems are constructed at, or near, the location of the hazardous waste which needs to be processed. In some instances, fixed systems can be built in pieces and then transported to a hazardous waste site. Thereafter, the pieces are put together to form one fixed system. Some fixed systems can also be broken down into their original pieces and transported to a new location. However, a fixed system cannot be frequently moved to a different location or position without risking damage to the system due to, among other things, vibrations and shocks encountered while the system is being moved. In sum, because fixed systems are not designed to be rugged or mobile, they would not survive being repeatedly moved from one location or position to another.
In reality, existing systems are designed to destroy hazardous waste at a certain location (xe2x80x9cexistingxe2x80x9d means systems, methods or devices other than those discovered by the present inventors). Each location will typically store one principle type of hazardous waste, such as ammunition, medical waste or nuclear waste. It should be understood that the term one type of hazardous waste does not mean that the waste cannot be composed of more than one constituent or composition. To the contrary, medical waste may contain many different types of constituents such as cardboard, plastics, glass and metal, However, it would be rare for one site to contain medical waste and ammunition or nuclear waste, for example.
Before going further, it should be understood that by xe2x80x9chazardous waste sitexe2x80x9d or xe2x80x9cwaste sitexe2x80x9d is meant the location of hazardous waste. This location may be the same location where the waste is generated or a different location, for example, where the waste is stored.
Typically, existing systems are not designed to destroy different types of hazardous waste. Therefore, it is impractical to move an existing system from one hazardous waste site containing one type of hazardous waste (e.g., asbestos) to a second hazardous waste site containing a second type of waste (e.g., medical waste). On the other hand, there is a need to develop ruggedized or mobile waste processing systems which are capable of being moved from one site to another and flexible enough to destroy more than one type of hazardous waste.
Existing systems are usually designed to take advantage of the utilities (e.g., water and power) present at a hazardous waste site. For example, existing systems are usually designed under the assumption that some hazardous waste locations have a ready supply of water and access to electrical power. Water is used in waste processing systems to help eliminate undesirable pollutants (e.g., particulate and acid gasses) generated when hazardous waste is processed as well as for cooling purposes. Problems occur when this assumption proves incorrect.
Accordingly, it is desirable to provide ruggedized methods and systems for processing hazardous waste.
It is also desirable to provide ruggedized methods and systems for processing hazardous waste which are flexible enough to process more than one type of hazardous waste.
It is yet further desirable to provide ruggedized methods and systems for processing hazardous waste which are capable of operating at hazardous waste sites which do not have sufficient water and/or power.
Other desires will become apparent to those skilled in the art from the following description taken in conjunction with the drawings and claims.
In accordance with the present invention there are provided ruggedized and flexible methods and systems for processing hazardous waste. Such methods and systems comprise a survivable waste processing vessel. One example of a survivable vessel comprises a self-sealing vessel adapted to substantially minimize stress (e.g., vibration plus road shock). Survivability of the vessel is further increased because the vessel comprises a cylindrical lower portion and a Roman-arch-shaped upper portion. Flexibility of the vessel is increased by adapting it to receive all three forms of waste; solids, liquids and gasses.
Further, such methods and systems can be outfitted with a switchable torch control unit adapted to rapidly switch a torch gas between air and an inert gas, such as nitrogen, from a gas supply to two plasma arc torches. This helps to control a critical oxygen to product gas ratio. Maintaining the ratio under a certain threshold is critical to ensure the safe operation of systems which are processing multiple types of hazardous waste.
The torches may comprise either non-transfer or transfer arc torches so as to more efficiently destroy both organic and inorganic wastes.
To maximize the life of an electrode within each torch, the switchable control unit is further adapted to rapidly control power to each torch independently over a range of 50% power to full power.
Problems associated with unavailable water supplies are solved by providing each system with a product gas cleaning unit which is adapted to, among other things, substantially eliminate a waste water slip stream by recirculating water within the system. Recirculation helps to substantially reduce the amount of water required by the system and eliminate a waste water slip stream.
The present invention also envisions an eductor adapted to maximize conversion of free carbon particulate byproducts so as to reduce carbon pollutants, by, among other things, injecting an oxidant into an extremely turbulent region.
Together, or individually, components of ruggedized systems envisioned by the present invention may be placed on one or more platforms, such as flat-bed trailers, each adapted to minimize road shock and vibration in order to allow the system to be moved from one location or position to another. To minimize shock and vibration each platform comprises a unibody construction and air ride suspension. Locating components of a system around an equipment center of gravity located substantially close to a floor of each platform gives the platform stability (e.g., as it moves around a curve).
Besides the systems described above, the present invention also envisions methods and programmed mediums (e.g., devices which store computer programs and/or code) adapted to control and carry out substantially the same features and functions.